Switching contact arrangement

ABSTRACT

A switching contact includes a rocker-type leaf spring as a contact force spring in order to produce the contact force required for a contact lever A drag bearing thereof is disposed between the point of rotation of the contact lever on a contact carrier and a contact-making end piece of the contact lever. Preferably, the drag bearing is formed by a bend of the contact force spring and a sliding surface disposed on the contact carrier. The drag bearing of the contact force spring can be displaced without a fixed link along the sliding surface according to the tension of the contact force spring. If the switching contract arrangement has several contact levers (multiple contact arrangement) all of the associated contact force springs can be combined to form a one-piece leaf spring.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/DE02/00485 which has an Internationalfiling date of Feb. 7, 2002, which designated the United States ofAmerica and which claims priority on German Patent Application number DE10108858.2 filed Feb. 14, 2001, the entire contents of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to a switching contactarrangement. Preferably, it relates to one including a contact mount anda contact lever which can move in an articulated manner about a rotationpoint on the contact mount, as well as a contact force spring,preferably in the form of a leaf spring, for pressing the contact leveragainst an opposing contact.

BACKGROUND OF THE INVENTION

A switching contact arrangement has been disclosed as a component of alow-voltage circuit breaker in U.S. Pat. No. 5,517,164.

The contact force which acts on the switching contacts of circuitbreakers is applied by stressing the contact force springs which havebeen mentioned, during the connection process. This is done by way of adrive apparatus which is part of the circuit breaker and whose switchingmovement is essentially constant throughout the intended life of thecircuit breaker. In contrast, erosion of the switching contactsincreases the travel of the contact lever, so that the contact forcedecreases in a corresponding manner to the erosion. If the aim is toensure that an adequate contact force is achieved even toward the end ofthe life of a switching contact arrangement, appropriate design of thecontact force springs can lead to an undesirably high contact force whentheir switching contact arrangement is new. This results in acorrespondingly large amount of energy being required for the driveapparatus.

SUMMARY OF THE INVENTION

An embodiment of the present invention is based on an object ofspecifying a circuit breaker in which the contact force depends to alesser extent on erosion of the contacts.

In the case of a switching contact arrangement of the type mentionedinitially, an embodiment of the invention, achieves an object in thatthe contact force spring is arranged such that it can pivot like arocker, such that the ends of the contact force spring rest on thecontact lever, and a pivoting bearing of the contact force spring isarranged between the rotation point of the contact lever and itscontact-making end part.

The contact force of the switching contact arrangement according to anembodiment of the invention does not follow the known characteristic ofa helical compression spring or of a single-armed leaf spring accordingto the cited U.S. Pat. No. 5,517,164. In fact, the dependency on thecontact erosion is largely reduced, and can largely be overcome byoptimized design of the geometry. The contact force is essentiallydefined by suitable choice of the prestresses. This also avoids thenecessity to derate the contact force spring and the drive apparatus,which has an advantageous effect on the life of the circuit breaker.

The pivoting bearing of the contact force spring can preferably movealong a sliding surface, which is located on the contact mount, as afunction of the respective spring force without any fixed connection tothe contact mount. The bearing point of the leaf spring arrangementvaries as a function of the position of the contact lever, since it isnot supported in a fixed position.

It has been found to be advantageous for the pivoting bearing for acontact force spring to be formed by a bend, which rests on theessentially planar sliding surface on the contact mount, in the contactforce spring.

In order to ensure that a defined force acts despite the fact that thepivoting bearing of the contact force spring can move relative to thecontact support, it is recommended that the relative movement of thecontact force spring with respect to the contact lever be restricted, orbe related to a specific point. This can be achieved by providing asliding core, which is seated on the contact mount as an opposingbearing for the contact force spring. It has also been found to beequally suitable, in order to form an opposing bearing for the contactforce spring, for one end of it to be bent, and for a recess to bearranged on the contact lever in order to hold the bent end.

As mentioned in the introduction, the subject matter of an embodiment ofthe invention includes the need to keep low the energy required tooperate the switching contact arrangement of a circuit breaker. This canbe contributed to by providing projections which are opposite oneanother with offset on the contact mount and on the contact lever in anarrangement, such that the spring force during connection of theswitching contact arrangement rises toward the end of the connectionmovement. Thus, the drive force to be provided by a drive apparatusrises less steeply when the contact lever is in contact with theopposing contact and even available kinetic energy can be used toachieve the required stress on the contact force springs when theswitching contact arrangement is in the connected state.

The embodiment of a switching contact arrangement according to anembodiment of the invention is particularly suitable for circuitbreakers with a high rated current, which have two or more contactlevers in each pole. The production and the assembly of thecorresponding number of contact force springs can be simplified by thecontact force springs of all the contact levers being a component of anintegral leaf spring.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail in the following textwith reference to exemplary embodiments which are illustrated in thefigures.

FIG. 1 shows a switching contact arrangement having two or more contactlevers, partially in the form of a section II—II in FIG. 2.

FIG. 2 shows the switching contact arrangement as shown in FIG. 1,looking at the parallel contact lever.

FIG. 3 shows a detail of the switching contact arrangement, shown on anenlarged scale, as in FIGS. 1 and 2.

FIGS. 4, 5 and 6 show a further exemplary embodiment, in illustrationswhich correspond to FIGS. 1, 2 and 3.

FIG. 7 shows a leaf spring which has contact force springs for two ormore contact levers, illustrated in perspective.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The switching contact arrangement which is illustrated in FIGS. 1, 2 and3 includes a contact mount 1 which is mounted by way of bearing pins 12in pivoting bearings which are not shown. Contact levers 2 are connectedto the contact mount 1, articulated about a rotation point 11. Thecontact levers 2 have a contact-making end part 18 and are electricallyconductively connected to a lower connecting rail 4 at the opposite endby way of flexible conductors 13, which are merely indicated. Contactforce springs 8 which are mounted like rockers are located between thecontact mount 1 and the contact levers 2 and ensure that thecontact-making end parts 18 of the contact levers 2 rest against anopposing contact 5, which is fitted with an arcing horn 3, with anadequate contact force when the switching contact arrangement is in theconnected state. The opposing contact 5 may be formed in a known mannerby one end of an upper connecting rail, which his arranged parallel tothe lower connecting rail 4.

FIG. 1 furthermore shows, schematically, a drive apparatus 6 which isknown per se, acts by way of a lever chain 7 on the contact mount 1, andmoves the latter to the connected or disconnected position. Togetherwith the protection and control devices that are not shown, saidassemblies form a low-voltage circuit breaker 22, as indicated by adash-dotted frame.

The contact force springs 8 of the individual contact levers 2 mayadmittedly be individual parts in the form of leaf springs, but are acomponent of a cohesive leaf spring, that is to say an integral leafspring. As can be seen in more detail in FIGS. 1 and 3, the contactforce springs 8 may have a bend 20 which is arranged approximately inthe center and which, together with a sliding surface 19 is formed onthe contact mount 1, forms a pivoting bearing 10. The essential featurefor the desired operation of the switching contact arrangement is theposition of the pivoting bearing 10 between the rotation point 11 of thecontact lever 2 and an upper end limb 14 of the contact force spring 8.This end limb 14 rests on the contact-making end part 18 of the contactlever 2, while an end limb 14, whose shape is approximately the same,rests on the contact lever 2 at the opposite end of the contact forcespring 8, approximately where the rotation point 11 is located. Thisarrangement has the characteristic that the contact force between thecontact-making end part 18 and the opposing contact 5 is largelyindependent of the relative position of the contact lever 2 with respectto the contact mount 1. The influence of the erosion of the interactivecontact points on the magnitude of the contact force is thus small.

In order to ensure that the required contact force is produced, theposition of the upper angled end part 14 of the contact force spring 8is a significant factor for given dimensions and characteristics of theinteracting parts. A sliding core 9, which is fitted to the contactmount 2, may be provided for this purpose. The pivoting bearing 10 ofthe arrangement 8 can move freely along the sliding surface 19 withoutany fixed connection to the contact mount 1, and is limited only by thesliding core 9, which is used as an opposing bearing, as a function ofthe stress in the contact force spring 8.

It should also be mentioned that the illustrated arrangement of therocker-like contact force spring 8 may be located in the space betweenthat side of the contact lever 2 which faces away from the contacts andthe contact mount 1, and may in this way be protected against influencesof switching arcs.

The further embodiment of a switching contact arrangement as illustratedin FIGS. 4 to 7 and having a large number of contact levers 2 (multiplecontact system) differs in the features described in the following textfrom the example illustrated in FIGS. 1 to 3. With regard to the rest ofthe embodiment, reference should be made to the description of theembodiment according to FIGS. 1 to 3.

While, in the first exemplary embodiment of the invention, the slidingcore 9 is used as a device for positioning the rocker-like contact forcespring 8, in the second embodiment of the invention as illustrated inFIGS. 4 to 7, the upper end limb 14 is bent in the direction of thecontact lever. The contact levers 2 are provided with a recess 15, inwhich the end limb 14 engages. This results in the contact force springs8 being aligned with respect to the associated contact levers. As in theexemplary embodiment shown in FIGS. 1, 2 and 3 as well, the desiredcontact force is achieved by fitting the contact force springs 8 in theswitching contact arrangement with a specific prestress.

The embodiment of two or more contact force springs 8 as an integralleaf spring 23 can be seen in more detail in FIGS. 5 and 7. In thiscase, FIG. 5 shows that the leaf spring 23 is located behind the contactlevers. Assembly is easy and may, for example, be carried out such thatthe leaf spring 23 is pushed into the intermediate space, after thecontact mount 1 and contact levers 2 have been joined together, untilthe angled end parts 14 latch into the recesses 25.

In order to reduce the amount of energy required for connection of acircuit breaker, it may be desirable for the contact force to beincreased to a desired value during connection only shortly before thecontact lever reaches the final position. As can clearly be seen in FIG.4 and FIG. 6, projections 16 and 17 are provided on the contact mount 1and on the contact lever 2, respectively, in order to achieve this aim,are opposite one another with an offset and are arranged such that thespring force is increased toward the end of the connection movement.

LIST OF REFERENCE SYMBOLS

-   1 Contact mount-   2 Contact lever-   3 Arcing horn on the opposing contact 5-   4 Lower connecting rail-   5 Opposing contact-   6 Drive apparatus-   7 Lever chain-   8 Rocker-like contact force spring-   9 Sliding core-   10 Pivoting bearing for the contact force spring-   11 Rotation point of the contact lever 2-   12 Pin for a pivoting bearing-   13 Flexible strips-   14 Angled end limb of the contact force spring 8-   15 Recess on the contact lever 2-   16 Projection on the contact mount 1-   17 Projection on the contact lever 2-   18 Contact-making end part of the contact lever 2-   19 Sliding surface on the contact mount 1-   20 Bend in the contact force spring 8-   21 Switching contact arrangement-   22 Circuit breaker-   23 Leaf spring with two or more contact force springs 8

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A switching contact arrangement, comprising: a contact mount; acontact lever, adapted to move in an articulated manner about a rotationpoint on the contact mount; and a contact force spring, adapted to exerta force against the contact lever, wherein the contact force spring isarranged to pivot, wherein both ends of the contact force spring rest onthe contact lever, and wherein a pivoting bearing of the contact forcespring is arranged approximately between the rotation point of thecontact lever and a contact-making end part of the contact lever.
 2. Theswitching contact arrangement as claimed in claim 1, wherein thepivoting bearing of the contact force spring is adapted to move along asliding surface of the contact mount, as a function of the respectivespring force, without any fixed connection to the contact mount.
 3. Theswitching contact arrangement as claimed in claim 1, wherein thepivoting bearing of the contact force spring is formed by a bend,resting on an essentially planar sliding surface on the contact mount,in the contact force spring.
 4. The switching contact arrangement asclaimed in claim 1, further comprising: a sliding core, seated on thecontact mount as an opposing bearing for the contact force spring. 5.The switching contact arrangement as claimed in claim 1, wherein, inorder to form an opposing bearing for the contact force spring, one endof the contact spring is bent, and a recess is arranged on the contactlever to hold the bent end.
 6. The switching contact arrangement asclaimed in claim 1, further comprising: projections, opposite oneanother with an offset on the contact mount and on the contact lever,arranged such that a spring force during connection of the switchingcontact arrangement rises toward the end of the connection movement. 7.The switching contact arrangement as claimed in claim 1, wherein theswitching contact arrangement is in the form of a multiple contactarrangement, and wherein the contact force springs of all the contactlevers are a component of an integral leaf spring.
 8. The switchingcontact arrangement as claimed in claim 1, wherein the contact forcespring is in the form of a leaf spring.
 9. The switching contactarrangement as claimed in claim 2, wherein the pivoting bearing of thecontact force spring is formed by a bend, resting on the sliding surfaceon the contact mount, in the contact force spring.
 10. The switchingcontact arrangement as claimed in claim 2, further comprising: a slidingcore, seated on the contact mount as an opposing bearing for the contactforce spring.
 11. The switching contact arrangement as claimed in claim3, wherein the pivoting bearing of the contact force spring is formed bya bend, resting on an essentially planar sliding surface on the contactmount, in the contact force spring.
 12. The switching contactarrangement as claimed in claim 3, further comprising: a sliding core,seated on the contact mount as an opposing bearing for the contact forcespring.
 13. The switching contact arrangement as claimed in claim 2,further comprising: projections, opposite one another with an offset onthe contact mount and on the contact lever, arranged such that a springforce during connection of the switching contact arrangement risestoward the end of the connection movement.
 14. The switching contactarrangement as claimed in claim 2, wherein the switching contactarrangement is in the form of a multiple contact arrangement, andwherein the contact force springs of all the contact levers are acomponent of an integral leaf spring.
 15. The switching contactarrangement as claimed in claim 3, further comprising: projections,opposite one another with an offset on the contact mount and on thecontact lever, arranged such that a spring force during connection ofthe switching contact arrangement rises toward the end of the connectionmovement.
 16. The switching contact arrangement as claimed in claim 3,wherein the switching contact arrangement is in the form of a multiplecontact arrangement, and wherein the contact force springs of all thecontact levers are a component of an integral leaf spring.
 17. Theswitching contact arrangement as claimed in claim 4, further comprising:projections, opposite one another with an offset on the contact mountand on the contact lever, arranged such that a spring force duringconnection of the switching contact arrangement rises toward the end ofthe connection movement.
 18. The switching contact arrangement asclaimed in claim 4, wherein the switching contact arrangement is in theform of a multiple contact arrangement, and wherein the contact forcesprings of all the contact levers are a component of an integral leafspring.
 19. The switching contact arrangement as claimed in claim 5,further comprising: projections, opposite one another with an offset onthe contact mount and on the contact lever, arranged such that a springforce during connection of the switching contact arrangement risestoward the end of the connection movement.
 20. The switching contactarrangement as claimed in claim 5, wherein the switching contactarrangement is in the form of a multiple contact arrangement, andwherein the contact force springs of all the contact levers are acomponent of an integral leaf spring.
 21. A switching contactarrangement, comprising: a contact mount; a lever, adapted to move abouta rotation point on the contact mount; and means for exerting a forceagainst the lever, wherein the means for exerting a force is arranged topivot, with both ends of the means for exerting a force resting on thelever, and wherein an angled surface of the means for exerting a forceis arranged approximately between the rotation point of the lever and acontact-making end part of the lever.
 22. The switching contactarrangement as claimed in patent claim 21, wherein a pivoting bearing atthe angled surface of the means for exerting a force is adapted to movealong a surface of the contact mount, as a function of a respectivespring force, without any fixed connection to the contact mount.
 23. Theswitching contact arrangement as claimed in claim 21, wherein a pivotingbearing of the means for exerting a force is formed by a bend in theexerting a force, resting on an essentially planar sliding surface ofthe contact mount.
 24. The switching contact arrangement as claimed inclaim 21, further comprising: a sliding core, arranged on the contactmount as an opposing bearing for the means for exerting a force.
 25. Theswitching contact arrangement as claimed in claim 21, wherein the meansfor exerting a force includes a spring, and wherein, in order to form anopposing bearing for the spring, one end of the spring is bent, andwherein a recess is arranged in the lever to hold the bent end.
 26. Theswitching contact arrangement as claimed in claim 21, furthercomprising: projections, opposite one another with an offset on thecontact mount and on the lever, arranged such that a spring force duringconnection of the switching contact arrangement rises toward the end ofthe connection movement.
 27. The switching contact arrangement asclaimed in claim 21, wherein the switching contact arrangement is in theform of a multiple contact arrangement, wherein the means for exerting aforce of each contact arrangement includes a spring, and wherein springsof all the levers are a component of an integral leaf spring.
 28. Theswitching contact arrangement as claimed in claim 21, wherein the meansfor exerting a force includes a leaf spring.
 29. A switching contactarrangement, comprising: a contact mount; a lever, adapted to move abouta rotation point on the contact mount; and means for exerting a forceagainst the lever, wherein the means for exerting a force is arranged topivot, with both ends of the means for exerting a force resting on thelever, and wherein a pivot bearing of the means for exerting a force isarranged approximately between the rotation point of the lever and acontact-making end part of the lever.
 30. The switching contactarrangement as claimed in patent claim 29, wherein the pivoting bearingis adapted to move along a surface of the contact mount, as a functionof a respective spring force, without any fixed connection to thecontact mount.
 31. The switching contact arrangement as claimed in claim29, wherein the pivoting bearing is formed by a bend in the exerting aforce, resting on the essentially planar sliding surface of the contactmount.
 32. The switching contact arrangement as claimed in claim 29,further comprising: a sliding core, arranged on the contact mount as anopposing bearing for the means for exerting a force.
 33. The switchingcontact arrangement as claimed in claim 29, wherein the means forexerting a force includes a spring, and wherein, in order to form anopposing bearing for the spring, one end of the spring is bent, andwherein a recess is arranged in the lever to hold the bent end.
 34. Aswitching contact arrangement, comprising: a contact mount; a lever,adapted to move about a rotation point on the contact mount; and aspring, adapted to exert a force against the lever, the spring beingarranged to pivot, with both ends of the spring resting on the lever,wherein a pivoting bearing of the spring is arranged approximatelybetween the rotation point of the lever and a contact-making end part ofthe lever.
 35. The switching contact arrangement as claimed in claim 34,wherein the spring is a leaf spring.
 36. The switching contactarrangement as claimed in patent claim 34, wherein the pivoting bearingis adapted to move along a surface of the contact mount, as a functionof a respective spring force, without any fixed connection to thecontact mount.
 37. The switching contact arrangement as claimed in claim34, wherein the pivoting bearing is formed by a bend in the exerting aforce, resting on the essentially planar sliding surface of the contactmount.
 38. The switching contact arrangement as claimed in claim 34,further comprising: a sliding core, arranged on the contact mount as anopposing bearing for the spring.
 39. The switching contact arrangementas claimed in claim 34, wherein, in order to form an opposing bearingfor the spring, one end of the spring is bent, and wherein a recess isarranged in the lever to hold the bent end.
 40. The switching contactarrangement as claimed in claim 1, wherein the spring is a contact forcespring.
 41. A circuit breaker comprising the switching contactarrangement of claim
 1. 42. A circuit breaker comprising the switchingcontact arrangement of claim
 21. 43. A circuit breaker comprising theswitching contact arrangement of claim
 29. 44. A circuit breakercomprising the switching contact arrangement of claim
 34. 45. Thecircuit breaker of claim 41, wherein the switching contact arrangementis mounted, via bearing pins, in pivoting bearings of the circuitbreaker.
 46. The circuit breaker of claim 42, wherein the switchingcontact arrangement is mounted, via bearing pins, in pivoting bearingsof the circuit breaker.
 47. The circuit breaker of claim 43, wherein theswitching contact arrangement is mounted, via bearing pins, in pivotingbearings of the circuit breaker.
 48. The circuit breaker of claim 44,wherein the switching contact arrangement is mounted, via bearing pins,in pivoting bearings of the circuit breaker.
 49. The switching contactarrangement as claimed in claim 21, wherein the lever is adapted to movein an articulated manner about a rotation point on the contact mount.50. The switching contact arrangement as claimed in claim 29, whereinthe lever is adapted to move in an articulated manner about a rotationpoint on the contact mount.
 51. The switching contact arrangement asclaimed in claim 34, wherein the lever is adapted to move in anarticulated manner about a rotation point on the contact mount.
 52. Theswitching contact arrangement as claimed in claim 34, wherein a firstend limb of the spring rests on a contact-making end part of the lever,and a second end limb rests on the lever approximately at the rotationpoint.
 53. The switching contact arrangement as claimed in claim 34,wherein the first end limb of the spring is angled up with respect tothe lever.
 54. The switching contact arrangement as claimed in claim 34,further comprising a sliding core, fitted to the contact mount, whereinthe first end limb of the spring is adapted to move between the slidingcore and the lever.
 55. The switching contact arrangement as claimed inclaim 54, wherein the pivoting bearing of the spring is adapted to movealong a surface of the contact mount, and is limited only by the slidingcore.
 56. The switching contact arrangement as claimed in claim 34,wherein the pivoting bearing of the spring is adapted to move along asurface of the contact mount, and is limited only by a sliding core. 57.The switching contact arrangement as claimed in claim 34, wherein afirst end limb of the spring is bent, and is adapted to rest in a recessarranged on the contact lever.
 58. The switching contact arrangement ofclaim 1, wherein the contact force spring is arranged to pivot like arocker.
 59. The switching contact arrangement of claim 21, wherein themeans for exerting a force is arranged to pivot like a rocker.
 60. Theswitching contact arrangement of claim 29, wherein the means forexerting a force is arranged to pivot like a rocker.
 61. The switchingcontact arrangement of claim 34, wherein the spring is arranged to pivotlike a rocker.